Tubular coupling

ABSTRACT

A tubular connection, method for connecting tubulars, and a coupler for connecting together tubulars, of which the tubular connection includes an inner body including a bore, external threads, a tapered torque nose, and a radially-facing sealing surface. The connection also includes an outer body including a bore in communication with the bore of the inner body, internal threads configured to engage the external threads of the inner body, a tapered torque-stop surface that engages the tapered torque nose, and a radially-facing sealing surface that forms a seal with the radially-facing sealing surface of the inner body. The external threads, the internal threads, or both include at least one kick-out feature including at least one rounded or chamfered corner thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/562,071, filed on Sep. 22, 2017. This application is also acontinuation-in-part of U.S. patent application Ser. No. 15/978,779,filed on May 14, 2018, which is a continuation-in-part of U.S. patentapplication Ser. No. 15/599,691, filed on May 19, 2017, which is acontinuation of U.S. patent application Ser. No. 15/254,793, filed onSep. 1, 2016 (now U.S. Pat. No. 6,983,684), which claims priority toU.S. Provisional Patent Application Ser. No. 62/381,468, filed on Aug.30, 2016, and U.S. Provisional Patent Application Ser. No. 62/265,222,filed on Dec. 9, 2015. Each of these priority applications isincorporated herein by reference in its entirety.

BACKGROUND

Tubular products (“tubulars”) are used in a variety of oilfieldapplications in which fluids are conveyed or isolated, and are found inboth surface and downhole applications. Several hundred to severalthousand feet of tubulars may be employed in such applications. Tubularsgenerally fall into two categories: continuous and jointed. Continuoustubulars are typically flexible and may be spooled or coiled fortransportation and unspooled for use. Jointed tubulars are often morerigid. Rather than spooling, these tubulars may be provided inrelatively short sections or “joints” and then connected together onsitefor the application. When such tubulars are connected or “made up”together, they are often referred to as a “string” of tubulars. Casingand drill pipe are two examples of jointed tubulars that may be madeinto such strings.

In the oilfield, tubulars may be sufficiently robust to withstand highpressure differentials across their walls. Further, the tubulars maysupport tensile/compressive loads and/or torsional loads. In jointedtubular strings, the connection between the tubulars thus also supportssuch loads. A variety of such tubular connections or “couplings” havebeen designed and implemented for such loads.

However, these tubular couplings often call for complex designs andexpensive specialty threading. Moreover, the couplings can represent afailure point in the tubular string. Thus, when the threads of thetubular itself, or of a coupling attached thereto, wear down, theaffected tubulars and/or couplings may be replaced with a new assembly,which incurs the costs associated with replacing such parts.

SUMMARY

Embodiments of the disclosure may provide a method for modifying atubular coupling. The method includes forming new threads in the tubularcoupling after the tubular coupling has been coupled to a tubularmember. The tubular coupling includes a body having a bore formedaxially-therethrough, internal threads formed on an inner surface of thebody that were used to couple the tubular coupling to the tubularmember, the new threads being a continuation of the internal threads,and a shoulder extending radially-inward from body with respect to theinternal threads, wherein forming the new threads comprises removing aportion of the shoulder.

Embodiments of the disclosure may also provide a method for modifying atubular coupling. The method includes forming new threads in the tubularcoupling after the tubular coupling has been coupled to first and secondtubular members. The tubular coupling includes a body having a firstaxial side and a second axial side, a first connector having firstinternal threads that are configured to couple with the first tubularmember, the first connector extending from the first axial side, thefirst connector defining a radially-facing sealing surface, a secondconnector having second internal threads that are configured to couplewith the second tubular member, the second connector extending from thesecond axial side, the second connector defining a radially-facingsealing surface, and the first and second connectors being in fluidcommunication with one another through the body, and a shoulderpositioned axially-between the first and second connectors. Forming thenew threads includes removing a portion of the shoulder. Further, thefirst internal threads and the new threads have a ratio of thread heightto pitch of between about 0.10 and about 0.20.

Embodiments of the disclosure may also provide a tubular couplingincluding a body having a bore formed axially-therethrough, and internalthreads formed on an inner surface of the body. The internal threadswere previously used to couple the tubular coupling to a tubular member.The body may also include new threads formed on the inner surface of thebody, the new threads being formed after the internal threads werepreviously used to couple the tubular coupling to the tubular member,the new threads being a continuation of the internal threads. The bodyalso includes a shoulder extending radially-inward from the body withrespect to the internal threads and the new threads, the new threadsbeing positioned axially-between the internal threads and the shoulder.

The foregoing summary is intended to introduce a subset of the aspectsof the present disclosure that are more fully described below. Thissummary is not intended to be exhaustive or to highlight key orimportant aspects of the disclosure, and should not be consideredlimiting on the scope of the following disclosure or the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may best be understood by referring to thefollowing description and accompanying drawings that are used toillustrate embodiments of the invention. In the drawings:

FIG. 1 illustrates a schematic view of a tubular string in a wellbore,according to an embodiment.

FIG. 2 illustrates a side, cross-sectional view of a first tubularattached to a second tubular using an integral coupling, according to anembodiment.

FIG. 3 illustrates a side, cross-sectional view of a first tubularconnected to a second tubular using a tubular coupling, according to anembodiment.

FIG. 4 illustrates a side, cross-sectional view of thread profiles forinner and outer bodies that are connected together, according to anembodiment.

FIGS. 5A, 5B, 5C, and 5D illustrate side, cross-sectional views ofthread profiles for inner and outer bodies that are connected together,according to an embodiment.

FIG. 6 illustrates a side, cross-sectional view of an inner bodyconnected to an outer body, according to an embodiment.

FIG. 7 illustrates another side, cross-sectional view of an inner bodyconnected to an outer body, according to an embodiment.

FIG. 8 illustrates an enlarged, partial, side, cross-sectional view ofan inner body connected to an outer body, according to an embodiment.

FIG. 9 illustrates a side, cross-sectional view of a tubular couplingthat couples together a first tubular and a second tubular, according toan embodiment.

FIGS. 10 and 11 illustrate side, cross-sectional views of twoembodiments of a tubular coupling that is configured to couple a firsttubular and a second tubular together, according to an embodiment.

FIG. 12 illustrates a flowchart of a method for connecting together twotubulars, according to an embodiment.

FIG. 13 illustrates a side, cross-sectional view of a first tubulardisconnected from a second tubular, according to an embodiment.

FIG. 14 illustrates a side, cross-sectional view of the first tubularand the second tubular after removing connectors thereof, according toan embodiment.

FIG. 15 illustrates a side, cross-sectional view of the first and secondtubulars being connected together using a tubular coupling, according toan embodiment.

FIG. 16 illustrates a side, cross-sectional view of the first and secondtubulars being connected together using a tubular coupling that includesone or more seals, according to an embodiment.

FIG. 17A illustrates an axial end view of a sealing element, accordingto an embodiment.

FIG. 17B illustrates a partial, side, cross-sectional view of a sealingelement, according to an embodiment.

FIGS. 18A-D illustrate side, cross-sectional views of the tubularcoupling during sequential stages of the method of FIG. 19, according toan embodiment.

FIG. 19 illustrates a flowchart of a method for modifying the tubularcoupling, according to an embodiment.

DETAILED DESCRIPTION

The following disclosure describes several embodiments for implementingdifferent features, structures, or functions of the invention.Embodiments of components, arrangements, and configurations aredescribed below to simplify the present disclosure; however, theseembodiments are provided merely as examples and are not intended tolimit the scope of the present disclosure. Additionally, the presentdisclosure may repeat reference characters (e.g., numerals) and/orletters in the various embodiments and across the Figures providedherein. This repetition is for the purpose of simplicity and clarity anddoes not in itself dictate a relationship between the variousembodiments and/or configurations discussed in the Figures. Moreover,the formation of a first feature over or on a second feature in thedescription that follows may include embodiments in which the first andsecond features are formed in direct contact, and may also includeembodiments in which additional features may be formed interposing thefirst and second features, such that the first and second features maynot be in direct contact. The embodiments presented below may becombined in any way, e.g., any element from one embodiment may be usedin any other embodiment, without departing from the scope of thedisclosure.

Additionally, certain terms are used throughout the followingdescription and claims to refer to particular components. As one skilledin the art will appreciate, various entities may refer to the samecomponent by different names, and as such, the naming convention for theelements described herein is not intended to limit the scope of theinvention, unless otherwise specifically defined herein. Further, thenaming convention used herein is not intended to distinguish betweencomponents that differ in name but not function. In the followingdiscussion and in the claims, the terms “including” and “comprising” areused in an open-ended fashion, and thus should be interpreted to mean“including, but not limited to.” All numerical values in this disclosuremay be exact or approximate values unless otherwise specifically stated.Accordingly, various embodiments of the disclosure may deviate from thenumbers, values, and ranges disclosed herein without departing from theintended scope. In addition, unless otherwise provided herein, “or”statements are intended to be non-exclusive; for example, the statement“A or B” should be considered to mean “A, B, or both A and B.”

In this disclosure, a connection made between an inner body and an outerbody is described, e.g., embodying a connection between two tubulars,whether directly together or via a tubular coupling. In someembodiments, the tubulars may initially be connected together, and itmay be determined that threads of one or both tubulars, or other partsof the tubulars, are unsuitable for continued use. As such, rather thanreplacing the tubulars and/or couplings, the regions including thethreads may be cut off or otherwise removed. New threads may then beformed on the exterior of the tubulars, and a tubular coupling may beprovided to connect the tubulars together. In some embodiments, thetubular coupling may be sized to make up the difference in the lengthsof the tubulars lost by cutting off the previous threaded connectors. Inother embodiments, the outer body may be provided by the second tubular,such that the two tubulars are connected directly together, therebyavoiding the need for a separate coupling. In some embodiments, thesecond tubular may be swaged outwards to form a new box-end (female)coupling, with the threads thereof being internal and formed therein forreceiving and engaging with the external, pin-end (male) threads of thefirst tubular. Various other aspects and embodiments will be describedbelow with specific reference to the embodiments of the Figures. Inaddition, the tubular connection will be described in relation to a2⅜-inch diameter tubing; however, it will be appreciated that thefeatures of the tubular connection described herein may be scaled foruse with a larger or a smaller diameter tubing.

Turning now to the specific, illustrated embodiments, FIG. 1 illustratesa side, schematic view of a tubular string 100 in a wellbore 102,according to an embodiment. The tubular string 100 may include aplurality of tubulars which may be connected together, end-to-end, e.g.,at the surface, and run into the wellbore 102. In particular, thetubular string 100 may include a first tubular 104 and a second tubular106. The first tubular 104 includes a tubular body 113 and a firstconnector 112. The first connector 112 may be externally threaded, e.g.,it may be a “pin-end” connector. The connector 112, as with the otherconnectors referred to herein, may be integrally formed with a remainderof the first tubular 104, or may be separately formed and coupledthereto.

Similarly, the second tubular 106 includes a tubular body 114 and asecond connector 116. The second connector 116 may be internally orexternally threaded in various embodiments. For example, if the firstand second tubulars 104, 106 are connected directly together, as shown,the second connector 116 may be an internally-threaded, “box-end”connector. As such, the second connector 116 may be configured toreceive the first connector 112. By rotating one or both of the firstand second tubulars 104, 106, the threads may engage and form a secureconnection therebetween. In other embodiments, as will be described ingreater detail below, a tubular coupling may be provided. In anembodiment, the coupling may have two internally-threaded connectors oneither axial end. As such, the second connector 116 may be externallythreaded, so as to connect with the internal threads of the tubularcoupling. It will be appreciated that embodiments are contemplated inwhich the coupling has one internally-threaded end and oneexternally-threaded end, and the second connector 116 may be internallythreaded in such embodiments. In other embodiments, the first and secondconnectors 112, 116 may be box-end connectors, and thus the tubularcoupling may include two pin-end connectors.

The tubular string 100 may also include a downhole tool 120 for use in awellbore operation. To name one specific example, among manycontemplated, the downhole tool 120 may be or include a milling device122 for use in a milling operation. The milling device 122 may beconfigured to mill out a packer 124 disposed in the wellbore 102 whenthe first and second tubulars 104, 106 are rotated. It will beappreciated that a variety of other downhole tools 120 may also orinstead be used. During the wellbore operation, the first and secondconnectors 112, 116 may be scarred and/or damaged, which may result inthe first and second tubulars 104, 106 failing, or a determination maybe made that the first and/or second tubulars 104, 106 have reached theend of their current lifecycles and are due to be replaced or repaired.

FIG. 2 illustrates a side, cross-sectional view of the first tubular 104connected to the second tubular 106, according to an embodiment. In thisembodiment, the first connector 112 of the first tubular 104 may bereceived into and directly coupled to the second connector 116 of thesecond tubular 106. As such, this arrangement may be considered an“integral” coupling between the first and second tubulars 104, 106.

Further, the first tubular 104 includes a generally cylindrical wall200, which may be of a generally constant diameter as proceeding alongthe tubular body 113, but may expand outwards proximal to the firstconnector 112. Such outward expansion may be accomplished by swaging oranother operation. Further, the thickness of the wall 200 may be reducedat the first connector 112, as threads 204 may be cut therein. In someembodiments, the wall 200 may be tapered at the first connector 112,such that the thickness of the wall 200, as well as the outer diameterthereof, decreases as proceeding along the first connector 112, awayfrom the tubular body 113. Such taper may provide increased tensile loadcapacity for the first connector 112, in comparison to non-taperedembodiments, which may lose tensile strength because of the reducedthickness of the wall 200 at the first connector 112.

The second tubular 106 may likewise include a generally cylindrical wall208, which may be generally constant in diameter as proceeding along thetubular body 114, but may expand radially outwards proximate to thesecond connector 116. Such outward expansion may be accomplished byswaging or another operation. Further, the thickness and outer diameterof the wall 208 may be reduced, e.g., tapered, at the second connector116. For example, the wall 208 may be tapered so as to receive thetapered geometry of the first connector 112, e.g., reverse orcomplementarily tapered. This may allow the second connector 116 toaccommodate receiving the first connector 112 therein. The secondconnector 116 may also include internal threads 210, which may beconfigured to engage the threads 204 of the first connector 112.

The first connector 112 may include a shoulder 213, a radially-facingsealing surface 211, and a torque nose 212 that defines anaxially-facing end of the first tubular 104. In some embodiments, theshoulder 213 and the torque nose 212 may be on opposite axial ends ofthe first connector 112, with the threads 204 being defined at leastpartially, e.g., entirely, therebetween. The sealing surface 211 may, inat least one embodiment, be positioned around an outer diameter of thewall 200, adjacent to the torque nose 212, e.g., extending axially fromthe torque nose 212. As the terms are used herein, “axial,” “axially,”and “axial direction” refer to a direction that is parallel to acentral, longitudinal axis of a cylindrical body. “Radial,” “radially,”and “radial direction” refer to a direction perpendicular to the axialdirection. “Radially-facing” means facing in the radial direction orboth the axial and radial directions (e.g., oriented at an angle).

The second connector 116 may include a stop surface 214, aradially-facing sealing surface 216, and an end surface 218. The stopsurface 214 may be positioned, shaped, or otherwise configured to engagethe torque nose 212, as will be described in greater detail below.Accordingly, when the first and second connectors 112, 116 are connectedtogether, the interaction between the torque nose 212 and the stopsurface 214 may prevent further axial movement of the first connector112 relative to the second connector 116. Similarly, the end surface 218may engage the shoulder 213 when the first and second connectors 112,116 are fully connected. The threads of the first and second connectors112, 116 may also be configured to interfere with one another as thefirst and second connectors 112, 116 are advanced together.

The sealing surface 216 may form a metal-to-metal seal with the sealingsurface 211 of the first connector 112. In some embodiments, the torquenose 212 and the stop surface 214 may also form a metal-to-metal seal,but in other embodiments, the torque nose 212 and the stop surface 214may not form such a seal. For example, forces incident on the first andsecond tubulars 104, 106 may cause the torque nose 212 and the stopsurface 214 to abrade against one another, or otherwise potentiallyaffect the integrity of a seal formed therebetween. Forming a sealbetween the sealing surface 216 and the sealing surface 211 generally inthe radial direction may avoid such damage and thus facilitatemaintaining a sealing interface between the first and second connectors112, 116. Further, in some embodiments, the end surface 218 may form ametal-to-metal seal with the shoulder 213, but in other embodiments, maynot. In addition, the seal between the surfaces 211 and 216 may beformed solely by applying a torque to the first tubular 104, the secondtubular 106, or both, e.g., without having to radially expand one or theother.

FIG. 3 illustrates a side, cross-sectional view of the first tubular 104connected to the second tubular 106 using a tubular coupling 300,according to an embodiment. The tubular coupling 300, in thisembodiment, may include two connectors 302A, 302B configured to engagethe first and second connectors 112, 116 of the first and secondtubulars 104, 106, respectively, and thereby couple the first and secondtubulars 104, 106 together, end-to-end. In some embodiments, the twoconnectors 302A, 302B of the tubular coupling 300 may be internallythreaded, e.g., box-end connectors. Moreover, the two connectors 302A,302B may be formed similarly to the second connector 116 shown in anddescribed above with reference to FIG. 2. Further, the first and secondconnectors 112, 116 may each be formed similarly to the first connector112 shown in and described above with reference to FIG. 2.

Considering the tubular coupling 300 in greater detail, the tubularcoupling 300 may include a body 304, in which the two connectors 302A,302B may be defined. Thus, the body 304 may define sealing surfaces306A, 306B, torque-stop surfaces 308A, 308B, and end surfaces 310A, 310Bfor the respective connectors 302A, 302B. In addition, the connectors302A, 302B may include threads 312A, 312B formed in the body 304, whichmay be configured to engage threads 314A, 314B of the first and secondconnectors 112, 116.

The sealing surfaces 306A, 306B may be on a radially-facing surface ofthe connectors 302A, 302B and may be configured to engage and form aseal with radial sealing surfaces 316A, 316B of the first and secondconnectors 112, 116. Further, the torque-stop surfaces 308A, 308B mayengage torque noses 318A, 318B, and the end surface 310A, 310B mayengage shoulders 320A, 320B of the first and second connectors 112, 116,e.g., potentially forming a seal therewith.

The body 304 of the tubular coupling 300 may define a central shoulder322 therein, which may partition the connectors 302A, 302B from oneanother. The central shoulder 322 may extend radially, increasing athickness of the body 304 between the connectors 302A, 302B. Forexample, the central shoulder 322 may cooperate with bores of the firstand second tubulars 104, 106 to provide a smooth, e.g., generallyconstant diameter bore 324 through the tubular coupling 300 when thefirst and second tubulars 104, 106 are connected thereto.

The two different types of connectors (e.g., using a tubular coupling asin FIG. 3 or integral connection as in FIG. 2) share in common theprovision of at least one inner body that is externally threaded and atleast one outer body that is internally threaded, with the inner andouter bodies being connected together via their threads. Thus, a varietyof embodiments for such connection are described below with reference toan inner body and an outer body, with it being appreciated that each maybe part of an oilfield tubular or part of a coupling.

FIG. 4 illustrates a side, cross-sectional view of a connection madebetween an outer body 400 and an inner body 402 using threads 404, 405,respectively, according to an embodiment. In particular, the threads 404may be internal and may be configured to engage the external threads 405formed in the inner body 402. The threads 404, 405 may each be formedfrom a single, helical ridge cut or otherwise formed in the respectivebody 400, 402, without departing from the scope of the term “threads,”which generally refers to the multiple crests and troughs that areapparent when viewing the thread form in cross-section. Accordingly, thethreads 404 may include crests 408 and troughs 412. Each crest 408 mayinclude a stabbing flank 406, an inner surface 409, and a load flank410. Similarly, the threads 405 may include crests 416 and troughs 420,with each crest 416 including a load flank 414, a stabbing flank 418,and an outer surface 419. When connected together, the load flanks 410,414 may be adjacent (e.g., may contact one another) and the stabbingflanks 406, 418 may be adjacent (e.g., may contact one another, or theremay be a gap formed therebetween).

A width W_(CB) of the crest 408 of the threads 404 may be definedbetween the stabbing flank 406 and the load flank 410. A width W_(TB) ofthe trough 412 of the threads 404 may be defined between the stabbingflank 406 and the load flank 410 of two adjacent crests 408. Similarly,a width W_(CP) of the crest 416 of the threads 405 may be definedbetween the load flank 414 and the stabbing flank 418. A width W_(TP) ofthe trough 420 may be defined between the stabbing flank 418 and theload flank 414 of adjacent crests 416. In an embodiment, the widthW_(CP) is between about 0.040 inches and about 0.136 inches, and thewidth W_(CB) is between about 0.039 inches and about 0.132 inches.

The widths W_(CP) and W_(CB) of the crests 408, 416 may, in someembodiments, be equal, about equal (e.g., within a certain tolerance),or different. Similarly, the widths W_(TP) and W_(TB) of the troughs412, 420 may be equal, about equal, or different. Further, the widthW_(TP) of the trough 412 may be larger than the width W_(CB) of thecrest 416, and the width W_(TB) of the trough 420 may be larger than thewidth W_(CP) of the crest 416. Accordingly, when the inner body 402 isthreaded into the outer body 400, a gap may be formed between thestabbing flank 418 of the thread 405 and the stabbing flank 406 of thethread 404, while the load flank 414 may engage the load flank 410. Thegap may be provided, among other things, potentially to receive andserve as a reservoir for a coating that may be applied to either or boththreads 404, 405.

In some embodiments, the threads 404, 405 may be constructed tointerfere and support a portion of the overall torque load, therebyreducing the loads between the torque-stop surface (e.g., 214 of FIG. 2)and the torque nose (e.g., 212 of FIG. 2). The interference may begenerated in a variety of manners, such as by running the crests 408,416 together or modifying the pitch along the length of the threads 404,405. For example, when the crest 416 is engaged with crest 408, e.g.,where the stabbing flank 406 meets the trough 412 (the “root” of thecrest 408), any further engagement of the outer and inner bodies 400,402 may urge the crest 416 into the crest 408, resulting ininterference. When the geometry of the threads 404, 405 is selected suchthat this interference occurs when the torque nose (e.g., 212 of FIG. 2)engages the torque-stop surface (e.g., 214 of FIG. 2), a portion of theapplied torque is carried at both locations (threads and torquenose/stop surface). As a result, the connection between the outer andinner bodies 400, 402 may be able to carry a higher torsional load thanit is capable of carrying when just the torque nose (e.g., 212 of FIG.2) and torque-stop surface (e.g., 214 of FIG. 2) are engaged.

The threads 404, 405 may include a kick-out feature, which mayfacilitate disconnection of the outer and inner bodies 400, 402. Forexample, after providing break-out torque to the connection, androtating the inner and outer bodies 400, 402 relative to one another, ina direction that causes the inner body 402 to withdraw from within theouter body 400, the threads 404, 405 may become less and less engagedwith the threads 405. This occurs due to the taper (as defined by ataper angle α, described below) of the connection. As the inner body 402is backed out from the outer body 400, at some point, the threads 404may be able to clear the threads 405, allowing for axial (linear)relative movement of the inner and outer bodies 400, 402. However,although the dimensions of the threads 404, 405 may allow for suchmovement, if the inner and outer bodies 400, 402 are not preciselycoaxial, the threads 404, 405 may become caught on one another,preventing the linear movement. The kick-out feature may alleviate thisdifficulty, avoiding at least some amount of hang-up between the threads404, 405. In addition, by provision of the kick-out feature, the torqueused to disconnect the threads 404, 405 may, in some example cases, beless than the torque used to make a full connection, e.g., between about1,000 ft-lbs and about 1,500 ft-lbs less.

In an embodiment, the kick-out feature may, for example, include roundedcorners of the threads 404, e.g., between the stabbing flank 406 and thetrough 412 of the thread 404, between the stabbing flank 406 and theinner surface 409, between the load flank 410 and the inner surface 409,and/or between the load flank 410 and the trough 412. In an embodiment,the corners of the threads 404 may define a radius r₁ of between about0.001 inches and about 0.010 inches, for example, about 0.005 inches. Itwill be appreciated that, in embodiments in which multiple corners arerounded, the radii of such rounding may be the same or different asbetween different corners.

Similarly, the threads 405 may be rounded as part of such a kick-outfeature. For example, the threads 405 may be rounded between the loadflank 414 and the trough 420, between the load flank 414 and the outersurface 419, between the stabbing flank 418 and the outer surface 419,and/or between the stabbing flank 418 and the trough 420. In anembodiment, the corners of the threads 405 may define a radius r₂ ofbetween about 0.010 inches and about 0.020 inches, or, for example,about 0.015 inches. It will be appreciated that, in embodiments in whichmultiple corners are rounded, the radii of such rounding may be the sameor different as between different corners.

In addition, the rounded corners of the threads 404, 405 (e.g., definingthe radii r₁ and r₂) may provide a smooth transition between surfaces ofthe threads 404, 405, which may limit stress risers and reduce thelikelihood of mechanical damage due to contact between the threadedsurfaces.

The pitch of the threads 404, 405 may vary from approximately 4 threadsper inch to 10 threads per inch. For example, four threads per inchcorresponds to a thread pitch value of approximately 0.25 inches; sixthreads per inch relates to approximately 0.167 inches; and 10 threadsper inch relates to approximately 0.100 inches, etc. The form of thethreads 404, 405 may thus be further described by the thread heightrelative to the thread pitch. In one embodiment, the thread height, thatis, the radial distance from where the load flank and stabbing flankmeet the trough to where the stabbing flank and load flank meet theouter or inner surface, is between about 10% and about 18% of the threadpitch, e.g., about 15% of the thread pitch. In an embodiment, the threadheight may be between about 0.020 inches and 0.030 inches or betweenabout 0.015 inches and about 0.038 inches. In an embodiment, the threads404, 405 may be asymmetric and may have a ratio of thread height topitch of between about 0.10 and about 0.20.

Considering the heights of the threads 404, 405 separately, the threads404 may have a height h_(B), and the threads 405 may have a heighth_(P). The height h_(B) may be smaller than the height h_(P), and thusthe aforementioned gap may also extend between corresponding troughs 420and the crests 408, while the crests 416 may engage the troughs 412. Inother embodiments, the height h_(P) may be equal to the height h_(B),such that interference may be generated. In an embodiment, the heighth_(P) may be between about 0.016 inches and about 0.038 inches, e.g.,between about 0.025 inches and about 0.029 inches, and the height h_(B)may be between about 0.015 inches and about 0.040 inches, e.g., betweenabout 0.016 inches and about 0.038 inches

In some embodiments, the ratio of the height h_(P) to an outer diameterof the inner body 402 (e.g., the first tubular 104 of FIG. 1) may bebetween about 0.0039 and about 0.0114. Further, the ratio of the heighth_(B) and an inner diameter of the outer body 400 may be between about0.0042 and about 0.0145.

By way of explanation, a relatively short thread may be prone to “threadjumping,” during which a crest received into a trough will leave thetrough and enter into an adjacent trough. Thread jumping can be anelastic or plastic event, and can damage the thread form and affect theconnection between the inner and outer bodies. A tapered connection mayincrease the axial to radial translation. In general, the taperincreases the angle of the flank which increases the radial component ofthe load. The taper also increases the likelihood of a thread jumpoccurring, because the engagement of the box and pin thread forms isreduced when the pin is moved axially out of the connection.Accordingly, conventional wisdom in some circumstances may be to avoid acombination of a tapered connection with relatively short threads, suchas the connection disclosed herein.

Additionally, when the threads 404, 405 are engaged in a manner that theroots (where the flanks and the troughs meet) and crests touch, theradial load component may be increased in the same manner as taperedparts being forced together. Larger tapers may stab more effectively,but have a larger axial to radial translation. Further, the outerdiameter and inner diameter of the threaded connectors have set values(related to the size of the tubulars of which they are a part), which inturn limits the available shoulder areas. A larger taper leaves lessavailable shouldering area which may limit the torsional capacity of theconnection.

Bending is an additional load component that also affects theconnection. When bending occurs, outer thread form (as viewed from theside) is subjected to additional axial tension, which results in anassociated increase in the radial component of thread loading.Additionally, bending may cause displacement in the connection, whichreduce the thread engagement between the threads 404, 405 and increasethe likelihood of a connection failure.

Overall, in some embodiments, the combination of pitch, thread height,and taper angle may allow the shouldering area to be maximized andsubstantially increases the torsional capacity of the connection.Further, the pitch and thread height combination results in a short,wide thread that is resistant to cross-threading and damage duringstabbing. For example, instead of cross-threading, the connection maylock during threading and not advance, thereby avoiding damage to thethreads.

Referring again to the specific example of the threads 404, 405 shown inFIG. 4, the corner between the load flank 414 and the outer surface 419of the threads 404 may be received into, and slide along the cornerbetween the load flank 410 and the trough 412 of the threads 405, as theconnection between the inner body 402 and the outer body 400 is made. Inaddition to providing a kick-out feature, the curving of the corners mayavoid causing a galling effect, or otherwise increasing a resistance todisconnecting the outer and inner bodies 400, 402. This may assist indisconnecting the outer and inner bodies 400, 402, and may thus formpart of the kick-out feature.

Further, the stabbing flanks 406, 414 and the load flanks 410, 418 maybe angled, e.g., forming acute angles γ₁, γ₂, γ₃, γ₄ with respect to theinner and outer surfaces 409, 419, as shown. Specifically, γ₁ may bedefined between the stabbing flank 406 and the inner surface 409, γ₂ maybe defined between the load flank 410 and the inner surface 409, γ₃ maybe defined between the stabbing flank 418 and the outer surface 419, andγ₄ may be defined between the load flank 418 and the outer surface 408.In some embodiments, the angles γ₁ and γ₂ may be the same, and theangles γ₃ and γ₄ may be the same (whether or not the same as the anglesγ₁ and γ₂), such that the respective threads 404, 405 are symmetric. Inother embodiments, the angles γ₁ and γ₂ and the angles γ₃ and γ₄ may bedifferent. For example, the angles γ₂ and γ₃ may be between about 70degrees and about 89 degrees, e.g., between about 79 degrees and about86 degrees, and the angles γ₁ and γ₄ may be between about 29 degrees andabout 70 degrees, e.g., about 60 degrees. Load flank angling mayminimize axial-to-radial translation and may facilitate stress flow fromthe thread itself to the tubular on which the connection is defined, andmay minimize “hot spots” of concentrated stress regions. The relativeangling of the threads 404, 405 may also assist with disconnection ofthe outer and inner bodies 400, 402, and may thus be considered part ofthe kick-out feature.

Further, the outer and inner bodies 400, 402 may be tapered. A taperedconnection typically increases the axial-to-radial translation. Ingeneral, the taper increases the angle of the flank which increases theradial component of the loading of the connection. The taper may alsoworsen any condition where a thread jump occurs, because the engagementof the box and pin thread forms is reduced when the pin (inner body) ismoved axially out of the connection. Additionally, when the box and pincomponents are engaged in a manner that the roots and crests of thethread forms touch, the radial load component is increased in the samemanner as tapered parts being forced together. Larger tapers typicallystab more easily, but may have a larger axial-to-radial translation.Further, the radial dimensions of the pin and box ends may have setvalues, related to the dimensions of the tubulars of which they are apart, which in turn may constrain the available shoulder areas. A largertaper leaves less available shouldering area which constrains thetorsional capacity of the connection.

For example, the outer and inner bodies 400, 402 may each define a taperangle α of between about 0.8 degrees and about 1.5 degrees, e.g., about1.2 degrees, with respect to a line drawn straight in the axialdirection, as shown. Generally, the angle α ranges within the valuesthat correspond to a diametral taper of 0.25 inch per foot to 1.00 inchper foot, e.g., between about 0.37 inches per foot and about 0.88 inchesper foot.

It will be appreciated that the relative shape and sizes of the threads404, 405 may be changed, which may change the surfaces thereof thatengage one another, or form gaps therebetween, as the inner body 402 andthe outer body 400 are connected together.

FIGS. 5A, 5B, 5C, and 5D illustrate side, cross-sectional views ofseveral embodiments of a connection made between an inner body 500 andan outer body 502. Beginning with FIG. 5A, the inner body 500 may be apin-end connector, e.g., of one of the tubulars of the tubular string100 discussed above with reference to FIG. 1, while the outer body 502may be a box-end connector of such tubulars, or of a tubular coupling,such as the tubular coupling 300 discussed above with reference to FIG.3.

The inner body 500 may include threads 504, a sealing surface 506, and atorque nose 508. The threads 504 may be or include an external helicalridge, which shown in cross-section, appears as a plurality of crests510 and troughs 512. Each of the crests 510 may include a load flank513, an outer surface 514, and a load flank 515. In an embodiment, asshown, the load flanks 513 may have a chamfered profile, e.g., defininga chamfer 517 between the load flank 513 and the outer surface 514, suchthat an angled surface takes the place of a sharp corner therebetween.

The outer body 502 may include threads 516, which may be a helicalinternal ridge that, in cross-section, appears as a plurality of crests518 and troughs 520. Each of the crests 518 may include a stabbing flank522, an inner surface 524, and a load flank 526. The load flanks 526 maybe shaped to receive and engage the load flanks 513, and thus may eachinclude an inverse chamfer 527 where the load flanks 526 meet thetroughs 520. Further, a gap may be defined between the load flanks 515and the stabbing flanks 522 when the inner body 500 is connected to theouter body 502 via the engaging threads 504, 516. Additionally, the gapmay extend between the inner surface 524 of the crest 518 and the trough512.

FIG. 5A also illustrates additional details of an embodiment of thetorque nose 508. As shown, the torque nose 508 may be tapered withrespect to a radial line, e.g., at an angle θ. The sealing surface 506may also be tapered with respect to an axial line, e.g., at an angle μ.The angle θ may, in some embodiments, be about three times the angle μ.This tapering may facilitate the formation of a seal between the sealingsurface 506 and a reciprocal sealing surface (not shown in FIGS. 5A-5D)of the outer body 502, such that the torque nose 508 and sealing surface506 form a wedge that drives into a corner between the torque-stopsurface (not shown in FIGS. 5A-5D) and the sealing surface.

FIG. 5B illustrates another embodiment of the threads 504, 516 of theinner and outer bodies 500, 502, respectively. In this embodiment, thecrest 510 may define an inverse chamfer 530 where the load flank 513meets the trough 512. Complementarily, the crest 518 may define achamfer 532 wherein the load flank 526 meets the inner surface 524.

FIG. 5C illustrates another embodiment of the threads 504, 516. In thisembodiment, the crest 518 defines a rounded, concave corner between theload flank 526 and the inner surface 524, while the crest 510 defines arounded, convex corner between the load flank 513 and the trough 512.

FIG. 5D illustrates yet another embodiment of the threads 504, 516. Inthis embodiment, the crest 510 defines a rounded, convex corner betweenthe load flank 513 and the outer surface 514, and a rounded, concavecorner between the load flank 513 and the trough 512. Further, the crest518 defines a rounded, convex corner between the load flank 526 and theinner surface 524. The rounded, concave corner between the load flank513 and the trough 512 may receive the rounded, convex corner betweenthe load flank 526 and the inner surface 524, and the rounded, convexcorner between the load flank 513 and the inner surface 524 may beprevented, by its shape, from engaging the rectilinear corner formedbetween the load flank 526 and the trough 520.

Accordingly, as shown, the threads 504 have a rounded corner between thetrough 512 and the load flank 513, and another rounded corner betweenthe load flank 513 and the outer surface 514. This creates an ‘S’-shapebetween the two adjacent, rounded corners. The corner between the loadflank 526 and the inner surface 524 of the threads 516 may besquared-off, rather than also forming an ‘S’-shape. Briefly, matingtogether two sets of threads with such an ‘S’-shape may presentchallenges as a consequence of manufacturing variability, which cancompromise the contact between the two thread forms. Compromised contactbetween the two thread forms can adversely affect the integrity of theoverall connection. Thus, in this embodiment, the inner surface 524 maybe spaced farther away from the trough 520 than in an ‘S’-shaped threadform, and the corner between the load flank 526, and inner surface 524may be squared-off, allowing for increased contact between the twothreads 504, 516. In particular, the line contact between load flank 526and load flank 513 may be maximized, regardless of manufacturingvariability.

FIG. 6 illustrates a side, cross-sectional view of an inner body 600received into and connected with an outer body 602, according to anembodiment. The inner body 600 may be a tubular, such as the firsttubular 104 discussed above with reference to FIG. 1. The outer body 602may be either the second tubular 106 (FIG. 1) or the coupling 300 (FIG.3).

The inner body 600 may include a torque nose 606, which may extend at anangle θ with respect to a line extending parallel to a central axis 608of the inner and outer bodies 600, 602. The outer body 602 may include atorque-stop surface 610, which may also extend at the angle θ, so as toengage the torque nose 606 when the inner body 600 is received therein.

Further, the outer body 602 may include a sealing surface 612 that facesgenerally radially inward (i.e., toward the central axis 608). In anembodiment, the sealing surface 612 may extend at the angle μ (see FIG.7). The inner body 600 may include a radially-facing sealing surface 614that faces generally radially outwards, and also extends at the angle μ.As noted above, the ratio of the angle θ to the angle μ may be about 3:1in some embodiments.

Accordingly, as the inner body 600 is advanced into the outer body 602,eventually the torque nose 606 may engage the torque-stop surface 610.These engaging tapered surfaces may thus cause the torque nose 606 to bedriven radially outwards by continued advancement of the inner body 600relative to the outer body 602. This may drive the sealing surfaces 612,614 together, forming a metal-to-metal seal therebetween.

Further, in some embodiments, threads 616 of the inner body 600 mayterminate before the torque nose 606, and threads 618 of the outer body602 may terminate before the torque-stop surface 610. A thread relief620 may be defined within the outer body 602, proximal to thetorque-stop surface 610. In some embodiments, a sealing element 622 maybe positioned therein, as shown. In other embodiments, such as thatshown in FIG. 7, a seal groove 700 may be defined in the outer body 602in which a sealing element 702 may be positioned. The sealing elements622, 702 may be any suitable sealing element, e.g., elastomeric,composite (e.g., carbon-fiber material), etc., in any suitable shape,e.g., rounded or square in cross-section, etc. Thread relief meant torun threader all the way across and stop.

FIG. 8 illustrates a side, cross-sectional view of another connectionbetween an inner body 800 and an outer body 802, according to anembodiment. As shown, the inner body 800 may include threads 804, whichmay engage with threads 805 of the outer body 802, so as to secure theconnection therebetween.

The inner body 800 may define a torque nose 814, which may engage atorque-stop surface 816 of the outer body 802 when the inner and outerbodies 800, 802 are connected together. The torque nose 814 and thetorque-stop surface 816 may each be at least partially curved incross-section, with the torque nose 814 being generally concave and thetorque-stop surface 816 being generally convex. At least part of thetorque nose 814 may thus form a structure analogous to a socket, and atleast part of the torque-stop surface 816 forms a structure analogous toa ball, such that the two together form an interface analogous to aball-and-socket joint. Further, a radial outer surface 818 of the innerbody 800, extending from and adjacent to the torque nose 814 may bespaced apart from a radial inner surface 820 of the outer body 802,extending from and adjacent to the torque-stop surface 816. Further, theradial inner surface 820 may be inclined at an angle λ with respect to aline drawn parallel to the central axis of the inner and outer bodies800, 802. Accordingly, the interface between the torque-stop surface 816and the torque nose 814 may allow for the inner body 800 and the outerbody 802 to flex at the connection, while minimizing or avoiding damagethereto.

FIG. 9 illustrates a side, cross-sectional view of a tubular coupling900 for connecting together a first tubular 902 and a second tubular904, according to an embodiment. The tubular coupling 900 may be similarto the tubular coupling 300 discussed above with reference to FIG. 3.The tubular coupling 900 may have a body 905 and may define a bore 906therethrough. The tubular coupling 900 may also define a first connector908 configured to receive and connect to the first tubular 902 and asecond connector 910 configured to receive and connect to the secondtubular 904. The first and second connectors 908, 910 may include anycombination of the features of the outer bodies discussed hereinabove.Further, the bore 906 may extend between the first and second connectors908, 910 so as to provide fluid communication therebetween, allowingcommunication between bores of the first and second tubulars 902, 904.

The body 905 may define an undercut section 912 therein, which may beformed as a radially-enlarged portion of the bore 906, between the firstand second connectors 908, 910. Accordingly, a thickness of the body 905at the undercut section 912 may be reduced as compared to regionsadjacent to the undercut section 912. This may facilitate bending of thetubular coupling 900 by reducing the bending stiffness thereof. Further,the undercut section 912 may serve as an inner profile for connectionwith a tool deployed into the tubulars. In other words, the undercutsection 912 may function as a “landing nipple.”

In one embodiment, the undercut section 912 is defined symmetricallyabout a centerline CL of the tubular coupling 900, with the centerlineCL extending radially at an axial middle of the body 905. In anotherembodiment, the undercut section 912 may be asymmetric about thecenterline CL. In an embodiment, the undercut section 912 may have alength B1 and a depth A1, as shown. The length B1 may be between about0.25 inches and about 4 inches along a longitudinal axis 914 of thetubular coupling 900. The depth A1 may be between about 0.1 inches andabout 0.5 inches.

Also shown, according to one example embodiment, is a taper 916, whichprovides a smooth transition from the bore 906 to the undercut section912. The taper 916 may reduce or avoid stress risers that may accompanyabrupt changes in geometry. The taper 916 may be between about 10 andabout 70 degrees relative to the longitudinal axis 914 of the tubularcoupling 900.

Additionally, a radius 920 is shown, as part of the specific,illustrated embodiment. The radius 920 provides a smooth transition fromthe taper 916 to the undercut section 912. The radius 920 may reducestress risers at the transition from the undercut section 912 to thetaper 916. The radius 920 may be between about 0.125 inches and about0.375 inches.

As shown in FIG. 9, the undercut section 912 has a profile that issubstantially parallel to the longitudinal axis 914 of the tubularcoupling 900. In another embodiment, the undercut section 912 may bedisposed at an angle relative to the longitudinal axis 914 of thetubular coupling 900. As also shown in FIG. 9, the undercut section 912has an inner diameter that is substantially the same along the length B1of the undercut section 912. In another embodiment, the undercut section912 may have more than one inner diameter along the length B1 of theundercut section 912, such that the undercut section 912 has a steppedprofile. The stepped profile of the undercut section 912 may be used asa landing or profile nipple for a wellbore operation, in someembodiments.

FIG. 10 illustrates a side, cross-sectional view of a tubular coupling1000, according to an embodiment. The tubular coupling 1000 may besimilar in structure and function to the tubular coupling 900, and maybe configured to receive and connect together two tubulars (not shown).As such, the tubular coupling 1000 may define a first connector 1002 anda second connector 1004, which may be internally threaded so as toconnect to the tubulars. The first and second connectors 1002, 1004 mayinclude any combination of the features of the outer bodies discussedhereinabove.

The tubular coupling 1000 may include a body 1006, in which a bore 1008is defined extending between the first and second connectors 1002, 1004,such that the tubulars may be in fluid communication with one anotherwhen connected to the tubular coupling 1000. Further, the body 1006 mayinclude an outer diameter surface 1010, which may extend substantiallyalong its axial length and may be generally cylindrical.

The body 1006 may also define a turndown section 1012 in the outerdiameter surface 1010, e.g., between the first and second connectors1002, 1004. The radial thickness of the body 1006 at the turndownsection 1012 may be reduced by provision of the turndown section 1012.In an embodiment, the turndown section 1012 may be defined symmetricallyabout a centerline CL of the tubular coupling 1000, but in otherembodiments, may be asymmetrical to the centerline CL. The turndownsection 1012 may be formed in the body 1006 using any suitable processor device, such as by cutting using a lathe, mill, or any other cuttingdevice or process, or as part of the formation of the tubular coupling1000 itself, e.g., casting, sintering, etc.

The turndown section 1012 may define a length B2 and a depth A2, asshown. The length B2 may be between about 0.25 inches and about 4 inchesalong a longitudinal axis 1014 of the tubular coupling 1000. The depthA2 may be between about 0.01 inches and about 0.5 inches.

Also shown is a taper 1016, which provides a smooth transition betweenthe turndown section 1012 and the adjacent regions of the outer diametersurface 1010 of the body 1006. The taper 1016 may prevent stress risersthat may accompany abrupt changes in geometry. Further, a radius 1018 isshown, which provides a smooth transition from the taper 1016 to theturndown section 1012. A radius 1020 is also shown, which provides asmooth transition from the taper 1016 to the outer diameter surface1010. The radii 1018 and 1020 may each be between about 0.060 inches andabout 0.375 inches. In addition to mitigating stress rises, the taper1016 and/or radii 1018, 1020 may provide a smooth geometry thatminimizes the chance of the turndown section 1012 catching or hanging upon changes in the wellbore or well-control stack during downholeoperations.

FIG. 11 illustrates a side, cross-sectional view of a tubular coupling1100 for connecting together two tubulars (not shown), according to anembodiment. The tubular coupling 1100 may be similar to the tubularcouplings 900, 1000 and similar features may be given the same referencenumbers. The tubular coupling 1100 may include first and secondconnectors 1102, 1104 having internal threads and being configured toreceive and connect together the two tubulars. The first and secondconnectors 1102, 1104 may include any combination of the features of theouter bodies discussed hereinabove. Further, the tubular coupling 1100may have a body 1106, in which a bore 1108 may be defined, extendingbetween the two connectors 1102, 1104, such that the tubulars mayfluidly communicate through the bore 1108 when connected to the body1106.

The tubular coupling 1100 may include both the undercut section 912 andthe turndown section 1012. In an embodiment, the undercut section 912and the turndown section 1012 may both be defined symmetrically aboutthe centerline CL, and may extend by about the same axial dimension,such that they are axially-aligned. As such, the radial thickness of thebody 1106 may be diminished by provision of both the undercut section912 and the turndown section 1012.

A method for coupling together two tubulars, e.g., using one of theembodiments of the tubular couplings described herein, may now beappreciated. FIG. 12 illustrates a flowchart of an example of such amethod 1200, according to an embodiment. In addition, FIGS. 13-15illustrate the structures employed with the method 1200 at variousstages of the method 1200, according to an embodiment.

The method 1200 may begin at 1202, by disconnecting a first tubular froma second tubular. Referring to FIG. 13, there is shown such a firsttubular 1302 disconnected from a second tubular 1304. In particular, thedisconnection may occur as part of routine oilfield operation (e.g.,“tripping out”), or in response to an event, such as a detection of afailure of a connection. The first tubular 1302 may be rotated relativeto the second tubular 1304, such that a pin-end connection 1306 of thefirst tubular 1302 is disengaged and removed from a box-end connection1308 of the second tubular 1304.

Referring again additionally to FIG. 12, the method 1200 may includedetermining that the pin-end connector 1306 and/or the box-end connector1308 are damaged, worn, or otherwise no longer safely, reliably suitedfor use, as at 1204. The method 1200 may then include removing thepin-end connector 1306 and the box-end connector 1308 from the first andsecond tubulars 1302, 1304, respectively, as at 1206, leaving tubularbodies 1305, 1307. FIG. 14 illustrates the first and second tubulars1302, 1304 after such removal. The removal of the pin-end connector 1306and the box-end connector 1308 may be accomplished using any suitablemethod, e.g., cutting with a saw, mill, lathe, torch, etc.

The method 1200 may then include forming external threads on theremaining tubular bodies 1305, 1307 of the first and second tubulars1302, 1304, as at 1208. FIG. 15 illustrates such external threads 1500,1502. The form of the threads 1500, 1502 may be substantially the same,or may be different. Further, one or both of the threads 1500, 1502 maytake the form of one or more of the thread forms described herein, e.g.,with respect to FIGS. 4 and/or 5A-5E. Stated otherwise, once cut andprovided with new threads 1500, 1502, the first and second tubulars1302, 1304 may each incorporate one or more embodiments of the innerbodies discussed hereinabove. Accordingly, one or both of the threads1500, 1502 may include kick-out features, and the first and secondtubulars 1302, 1304 may include tapered torque noses, radial sealingsurfaces, etc.

Referring again to FIG. 12 and advancing in the method 1200, the method1200 may include connecting the first and second tubulars 1302, 1304together by connecting the threads 1500, 1502 to a tubular coupling1506, which is also illustrated in FIG. 15. The tubular coupling 1506may be or include any combination of features described above for thevarious tubular couplings and/or outer bodies, e.g., undercut sections,turndown sections, radial sealing surface, torque-stop surfaces, threadreliefs, etc. Further, the tubular coupling 1506 may define an axiallength L. The axial length L may be sufficient not only to receive thethreads 1500, 1502 of the tubulars 1302, 1304 therein, but also toincrease the length of the combination of the first and second tubulars1302, 1304 to compensate for the removed pin-end connector 1306 and thebox-end connector 1308.

In some embodiments, the coupling 1506 may include one or more spirals(not shown) on an outer surface of the tubular coupling. The spiral maybe formed in the outer surface of the tubular coupling by a machiningprocess (e.g., machining a groove or a protrusion). The spiral may alsobe formed on the outer surface from one or more layers of a thermalspray, such as WEARSOX®, which is commercially available from AntelopeOil Tool & Mfg. Co., LLC. The spiral may be configured to reduce thesurface area of the tubular coupling in contact with the surroundingwellbore during the wellbore operation. Further, the spiral may beconfigured to agitate debris from the wellbore by directing flowgenerated as the tubular coupling is rotated during the wellboreoperation, particularly in a highly deviated wellbore. The spiral mayalso reduce the friction between the tubular coupling and thesurrounding wellbore because the tubular coupling is lifted. In oneembodiment, one or more horizontal or vertical grooves (or protrusions)may be used in place of the spiral.

FIG. 16 illustrates a side, cross-sectional view of a connection 1600including an inner body 1602 and an outer body 1604, according to anembodiment. The inner body 1602 may be a tubular, and, as shown, theouter body 1604 may be a coupling, similar to the coupling 300 discussedabove with respect to FIG. 3, or may be a second tubular, e.g., asdiscussed with respect to FIG. 2.

In the illustrated embodiment, the outer body 1604 may include a firstconnector 1606 and a second connector 1608, which may be incommunication with one another via a bore 1610 defined through the outerbody 1604. Further, a shoulder 1611 may be defined between the first andsecond connectors 1606, 1608. The first connector 1606 may be configuredto receive and connect to the inner body 1602, as shown. The secondconnector 1608 may be configured to connect with another tubular (notshown). For example, the first connector 1606 may include first internalthreads 1612 and the second connector may include second internalthreads 1614. The first internal threads 1612 may be configured toengage external threads 1615 of the inner body 1602.

Either or both of the first and second connectors 1606, 1608 may includeone or more seals. For example, as shown, the first connector 1606 mayinclude an inboard seal 1616 and an outboard seal 1618. The secondconnector 1608 may also include an inboard seal 1620 and an outboardseal 1622. However, it will be appreciated that any combination of sidesand seals may be employed (e.g., one or more of the illustrated sealsmay be omitted) without departing from the scope of the presentdisclosure.

Each of the seals 1616, 1618, 1620, 1622, if present, may be seated intoa recess or groove formed in the outer body 1604 and extending outwardstherefrom. The seals 1616, 1618, 1620, 1622 may be configured to engage,e.g., seal with, the outer circumferential surface of the inner body1602 (in the case of the seals 1616, 1618; and another, not depicted,inner body in the case of the seals 1620, 1622).

The seals 1616, 1618, 1620, 1622 may be separated axially apart, e.g.,may be positioned on or proximate to opposite axial sides of theconnectors 1606, 1608, respectively. For example, the inboard seal 1616may be positioned axially between the outboard seal 1618 and theshoulder 1611. Similarly, the inboard seal 1620 may be positionedbetween the shoulder 1611 and the outboard seal 1622.

The inboard seals 1616, 1620 provide an auxiliary seal (in addition to ametal-to-metal seal formed between the inner body 1602 and the outerbody 1604 as described above). The inboard seals 1616, 1620 may belocated in a region that already has tight/controlled tolerances, whichlends itself to producing a better seal. Additionally, in this position,smooth machined or formed surfaces may be in contact with the sealduring the makeup of the connection, rather than potentially un-machinedor rough surfaces.

The outboard seals 1618, 1622 may protect of the threads 1612, 1614 bypreventing ingress of fluid to between the engaged threads 1612, 1614during use. Thus, a sealed chamber may be effectively created between aprimary metal-to-metal seal at or near to the nose of the inner body (orbodies) 1602 and the outboard seals 1618, 1622.

A dual-seal configuration including both sets of seals 1616, 1618, 1620,1622 may combine the functionalities of these two sealing locations. Inaddition, in some embodiments, the grooves or recesses may be formed inthe outer body 1604, but the sealing element may be omitted from one ormore of these grooves. This may facilitate inventory management, forexample.

FIGS. 17A and 17B illustrate an axial end view and a partial, side,cross-sectional view, respectively, of a sealing element 1700, accordingto an embodiment. In particular, as indicated, the view of FIG. 17B istaken along line 17B-17B in FIG. 17A.

In an embodiment, the sealing element 1700 may be employed for any oneof the seals 1616, 1618, 1620, and/or 1622. Referring specifically toFIG. 17B, the sealing element 1700 may have a cross-sectional shape,which may, for example, include one or more outer ridges (two are shown:1702, 1704). The outer ridges 1702, 1704 may extend from an outer radialsurface 1706 of the sealing element 1700. The outer ridges 1702, 1704may be separated apart, which may allow for a degree of deflection orcompression of the outer ridges 1702, 1704, e.g., pressing the sealingelement 1700 into the outer body 1604 (FIG. 16). For example, this mayaccommodate thermal expansion or any other factor resulting in radialexpansion, e.g., of the inner body 1602 (FIG. 16) relative to the outerbody 1604.

Further, as seen in the cross-section of FIG. 17B, the sealing element1700 may also include a tapered inner surface 1707 on a radial insidethereof. The inner surface 1707 may include one or more inner ridges(one shown: 1708). The inner ridge 1708 may be positioned or otherwiseconfigured to engage an inner body (e.g., the inner body 1602 of FIG.16), and may be configured or otherwise able to deflect or compress, soas to account for expansion of the inner body while maintaining sealintegrity. Additionally, the sealing element 1700 may have flat axialsides 1710, 1712, which may facilitate fitting the sealing element 1700snugly in a square sealing recess, e.g., as compared to a rounded O-ringor the like.

FIGS. 18A-18D illustrate cross-sectional views of a tubular coupling1800A-D during sequential stages of a method 1900 (described below). Asshown in FIG. 18A, the tubular coupling 1800A may be similar to thetubular coupling 300 described above. For example, the tubular coupling1800A may include two connectors 1802A, 1802B configured to engagecorresponding connectors of first and second tubulars. The twoconnectors 1802A, 1802B may be internally threaded (e.g., box-endconnectors).

The tubular coupling 1800A may also include a body 1804, in which thetwo connectors 1802A, 1802B may be defined. The body 1804 may definesealing surfaces 1806A, 1806B. The sealing surfaces 1806A, 1806B may beon a radially-facing surface of the two connectors 1802A, 1802B and maybe configured to engage and form a seal with corresponding radialsealing surfaces of the first and second tubulars. The body 1804 mayalso define torque-stop surfaces 1808A, 1808B. The torque-stop surfaces1808A, 1808B may be configured to engage torque noses of the first andsecond tubulars when connected thereto. The body 1804 may also defineend surfaces 1810A, 1810B. The end surfaces 1810A, 1810B may beconfigured to engage shoulders of the first and second tubulars. Thebody 1804 may also define threads 1812A, 1812B, which may be configuredto engage corresponding threads of the first and second tubulars. Thethreads 1812A, 1812B may be formed as or similar to any of the threadshapes disclosed herein and/or others. In at least one embodiment, thethreads 1812A, 1812B may be internal threads that include at least onekick-out feature including, e.g., a rounded or chamfered corner thereof(e.g., as described above with respect to FIG. 4). The body 1804 mayalso define a central shoulder 1822 therein, which may partition the twoconnectors 1802A, 1802B from one another. The central shoulder 1822 mayextend radially inward, increasing a thickness of the body 1804 betweenthe two connectors 1802A, 1802B. The body 1804 may also define one ormore inboard and/or outboard circumferential grooves for receivingsealing elements (e.g., as described above with respect to FIGS. 16 and17).

As shown, when the tubular coupling 1800A has a first length 1830A, thetwo connectors 1802A, 1802B may each have a length 1832A, 1832B, and theshoulder 1822 may have a length 1834A. For example, when the firstlength 1830 is from about 10 inches to about 15 inches (e.g., 13.325inches), the length(s) of the first and second connectors 1832A, 1832Bmay be from about 3 inches to about 5 inches (e.g., about 3.75 inches),and the length 1834 of the shoulder 1822 may be from about 2 inches toabout 5 inches (e.g., about 3.132 inches). The two connectors 1802A,1802B may each have a radial thickness 1836 that decreases proceedingaxially away from the shoulder 1822.

In some embodiments, after the tubular coupling 1800A is used (e.g., forthe first time), the tubular coupling 1800A may be damaged. For example,the threads 1812A, 1812B may deform during use. When this occurs, thetubular coupling 1800A may be modified to produce the tubular coupling1800B (in FIG. 18B), which may be suitable for subsequent use.

FIG. 19 illustrates a flowchart of a method 1900 for modifying thetubular coupling 1800A, according to an embodiment. As explained ingreater detail below, the tubular coupling 1800A may be modified toextend the life the tubular coupling 1800A so that the tubular coupling1800A may be reused one or more times. The method 1900 may be viewedtogether with FIGS. 18A-D. It will be appreciated that the method 1900may apply to any of the tubular couplings and any of the threadconfigurations described herein.

The method 1900 may include re-forming the threads 1812A, 1812B in thetwo connectors 1802A, 1802B, as at 1902. Re-forming the threads 1812A,1812B may include inserting a tool into the bore defined by theconnectors 1802A, 1802B and cutting, machining, etc. the inner radialsurfaces of the connectors 1802A, 1802B with the tool, which may removeor smooth over any deformation of the threads 1812A, 1812B. In at leastone embodiment, the tool used to re-form the threads may be the sametool that was used to initially form the threads 1812A, 1812B.

The method 1900 may also include forming first new threads 1814A, 1814Bas an extension/continuation of the threads 1812A, 1812B, as at 1904.This is shown in FIG. 18B. Thus, the first new threads 1814A, 1814B mayhave the same shape (e.g., thread height, pitch, etc.) as the threads1812A, 1812B. In some embodiments, the threads 1814A, 1814B may beformed as or similar to any of the thread shapes disclosed herein and/orothers, whether or not the same as the threads 1812A, 1812B. The shapeof the threads 1812A, 1812B and the first new threads 1814A, 1814B maybe the same as any of the threads disclosed in previous embodiments ofthis application. Forming the first new threads 1814A, 1814B may includepushing the tool into the bore until the tool contacts the shoulder1822. The tool may then remove a portion of the shoulder 1822 (e.g., bycutting, machining, etc. the shoulder 1822), thereby reducing the length1834A of the shoulder 1822. This may cause the shoulder 1822 to have asecond length 1834B that is less than the first length 1834A. Forexample, the length 1834B may be from about 3 inches to about 6 inches(e.g., about 4.382 inches).

In at least one embodiment, the tool may cut, machine, etc. the firstnew threads 1814A, 1814B in the inner radial surfaces of the connectors1802A, 1802B simultaneously with the cutting, machining, etc. of theshoulder 1822 to reduce the length 1834A of the shoulder 1822. Inanother embodiment, the tool may be removed after cutting, machining,etc. the shoulder 1822 to reduce the length 1834A of the shoulder 1822,and a second tool may be inserted into the bore to cut, machine, etc.the first new threads 1814A, 1814B in the inner radial surfaces of theconnectors 1802A, 1802B.

In embodiments in which the radial thickness 1836 of the connectors1802A, 1802B decreases proceeding away from the shoulder 19822,re-forming the threads 1812A, 1812B and/or forming the first new threads1814A, 1814B may reduce the wall thickness 1836 of the connectors 1802A,1802B. This may decrease the structural integrity of the connectors1802A, 1802B proximate to the axial ends 1810A, 1810B thereof. Thus, themethod 1900 may also include removing a portion of an axial end 1810A,1810B of each of the connectors 1802A, 1802B, as at 1906. This may causethe tubular coupling 1800B to have a second length 1830B that is lessthan the first length 1830A. For example, after removal, the length1830B may be from about 10 inches to about 13 inches (e.g., about 11.875inches). After the length of the connectors 1802A, 1802B is increased(e.g., by cutting, machining, etc. the shoulder 1822 to reduce thelength 1834A of the shoulder 1822) and decreased (e.g., by removing aportion of an axial end of each of the connectors 1802A, 1802B), theconnectors 1802A, 1802B may have substantially the same length 1832(e.g., within 0.5 inches) in FIG. 18B as they had in FIG. 18A. In otherwords, a length of the portion of the shoulder 1822 that is removed maybe substantially equivalent (e.g., within 0.5 inches) to an aggregate ofthe lengths of the portions of the axial ends 1810A, 1810B) of the body1804 that are removed.

Blocks 1902, 1904, 1906 may occur in any order. In one example, thethreads 1812A, 1812B may be re-formed, and then the first new threads1814A, 1814B may be formed, and then the portion of the axial end 1810A,1810B of each of the connectors 1802A, 1802B may be removed. In anotherexample, the threads 1812A, 1812B may be re-formed simultaneously withthe first new threads 1814A, 1814B being formed, and then the portion ofthe axial end 1810A, 1810B of each of the connectors 1802A, 1802B may beremoved. In yet another example, the portion of the axial end 1810A,1810B of each of the connectors 1802A, 1802B may be removed prior tore-forming the threads 1812A, 1812B and the forming of the first newthreads 1814A, 1814B. In at least one embodiment, new inboard and/oroutboard circumferential grooves may be formed in the body 1804 forreceiving sealing elements (e.g., as described above with respect toFIGS. 16 and 17). This may take place before, simultaneously with, orafter any of blocks 1902, 1904, or 1906.

The method 1900 may also include connecting a first tubular and a secondtubular together via the tubular coupling 1800B, as at 1908. This maybe, for example, the second time that the tubular coupling 1800B isused. As mentioned above, this use of the tubular coupling 1800B maycause the tubular coupling 1800B to be damaged and potentiallyunsuitable for subsequent use. For example, the threads 1812A, 1812B,1814A, 1814B may deform during use. When this occurs, the followingblocks 1910, 1912, 1914 may modify the tubular coupling 1800B (in FIG.18B) to produce the tubular coupling 1800C (in FIG. 18C), which may besuitable for subsequent use.

More particularly, the method 1900 may include re-forming the threads1812A, 1812B, 1814A, 1814B in the two connectors 1802A, 1802B, as at1910. The method 1900 may also include forming second new threads 1816A,1816B as an extension/continuation of the first new threads 1814A,1814B, as at 1912. This is shown in FIG. 18C. This may cause theshoulder 1822 to have a third length 1834C that is less than the secondlength 1834B. For example, the length 1834C may be from about 2 inchesto about 3 inches (e.g., about 2.632 inches).

The method 1900 may also include removing a portion of the axial end1810A, 1810B of each of the connectors 1802A, 1802B, as at 1914. Thismay cause the tubular coupling 1800C to have a third length 1830C thatis less than the second length 1830B. For example, after removal, thelength 1830C may be from about 9 inches to about 11 inches (e.g., about10.125 inches). After the length of the connectors 1802A, 1802B isincreased (e.g., by cutting, machining, etc. the shoulder 1822 to reducethe length 1834B of the shoulder 1822) and decreased (e.g., by removinga portion of an axial end of each of the connectors 1802A, 1802B), theconnectors 1802A, 1802B may have the same length 1832 in FIG. 18C asthey had in FIG. 18B.

The method 1900 may also include connecting a third tubular and a fourthtubular together via the tubular coupling 1800C, as at 1916. This maybe, for example, the third time that the tubular coupling 1800C is used.As mentioned above, this use of the tubular coupling 1800C may cause thetubular coupling 1800C to be damaged and potentially unsuitable forsubsequent use. For example, the threads 1812A, 1812B, 1814A, 1814B,1816A, 1816B may deform during use. When this occurs, the followingblocks 1918, 1920, 1922 may modify the tubular coupling 1800C (in FIG.18C) to produce the tubular coupling 1800D (in FIG. 18D), which may besuitable for subsequent use.

More particularly, the method 1900 may also include re-forming thethreads 1812A, 1812B, 1814A, 1814B, 1816A, 1816B in the two connectors1802A, 1802B, as at 1918. The method 1900 may also include forming thirdnew threads 1818A, 1818B as an extension/continuation of the second newthreads 1816A, 1916B, as at 1920. This is shown in FIG. 18D. This maycause the shoulder 1822 to have a fourth length 1834D that is less thanthe third length 1834C. For example, the length 1834D may be from about0.5 inches to about 1.5 inches (e.g., about 0.882 inches).

The method 1900 may also include removing a portion of the axial end1810A, 1810B of each of the connectors 1802A, 1802B, as at 1922. Thismay cause the tubular coupling 1800D to have a fourth length 1830D thatis less than the third length 1830C. For example, after removal, thelength 1830D may be from about 7 inches to about 10 inches (e.g., about8.375 inches). After the length of the connectors 1802A, 1802B isincreased (e.g., by cutting, machining, etc. the shoulder 1822 to reducethe length 1834C of the shoulder 1822) and decreased (e.g., by removinga portion of an axial end of each of the connectors 1802A, 1802B), theconnectors 1802A, 1802B may have the same length 1832 in FIG. 18D asthey had in FIG. 18C.

The method 1900 may also include connecting a fifth tubular and a sixthtubular together via the tubular coupling 1800D, as at 1924. This maybe, for example, the fourth time that the tubular coupling 1800D isused. As mentioned above, this use of the tubular coupling 1800D maycause the tubular coupling 1800D to be damaged and potentiallyunsuitable for subsequent use. For example, the threads 1812A, 1812B,1814A, 1814B, 1816A, 1816B, 1818A, 1818B may deform during use. Themethod 1900 may conclude when the length 1834D of the shoulder 1822 isnot long enough for another round of modifications (e.g., as at blocks1904, 1912, 1920).

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the present disclosure. Thoseskilled in the art should appreciate that they may readily use thepresent disclosure as a basis for designing or modifying other processesand structures for carrying out the same purposes and/or achieving thesame advantages of the embodiments introduced herein. Those skilled inthe art should also realize that such equivalent constructions do notdepart from the spirit and scope of the present disclosure, and thatthey may make various changes, substitutions, and alterations hereinwithout departing from the spirit and scope of the present disclosure.

What is claimed is:
 1. A method for modifying a tubular coupling,comprising: forming new threads in the tubular coupling after thetubular coupling has been coupled to a tubular member, wherein thetubular coupling comprises: a body having a bore formedaxially-therethrough; internal threads formed on an inner surface of thebody that were used to couple the tubular coupling to the tubularmember, wherein the new threads are a continuation of the internalthreads; and a shoulder extending radially-inward from body with respectto the internal threads, wherein forming the new threads comprisesremoving a portion of the shoulder.
 2. The method of claim 1, furthercomprising re-forming at least a portion of the internal threads afterthe tubular coupling has been coupled to the tubular member.
 3. Themethod of claim 1, further comprising removing a portion of an axial endof the body, such that a length of the body is reduced.
 4. The method ofclaim 3, wherein the portion of the axial end of the body is removedafter the new threads are formed.
 5. The method of claim 3, wherein theportion of the axial end of the body is removed before the new threadsare formed.
 6. The method of claim 3, wherein a length of the portion ofthe shoulder that is removed is substantially equivalent to a length ofthe portion of the axial end of the body that is removed.
 7. The methodof claim 3, wherein a radial thickness of the body decreases proceedingtoward the axial end of the body.
 8. The method of claim 1, wherein thenew threads have a ratio of thread height to pitch of between about 0.10and 0.20, and wherein the new threads have at least one kick-out featureincluding at least one rounded or chamfered corner thereof.
 9. A methodfor modifying a tubular coupling, comprising: forming new threads in thetubular coupling after the tubular coupling has been coupled to firstand second tubular members, wherein the tubular coupling comprises: abody having a first axial side and a second axial side; a firstconnector having first internal threads that are configured to couplewith the first tubular member, the first connector extending from thefirst axial side, the first connector defining a radially-facing sealingsurface; a second connector having second internal threads that areconfigured to couple with the second tubular member, the secondconnector extending from the second axial side, the second connectordefining a radially-facing sealing surface, and the first and secondconnectors being in fluid communication with one another through thebody; and a shoulder positioned axially-between the first and secondconnectors, wherein forming the new threads comprises removing a portionof the shoulder, and wherein the first internal threads and the newthreads have a ratio of thread height to pitch of between about 0.10 andabout 0.20
 10. The method of claim 9, further comprising re-forming thefirst and second internal threads after the tubular coupling has beencoupled to the first and second tubular members.
 11. The method of claim9, further comprising: removing a portion of the first axial side of thebody; and removing a portion of the second axial side of the body. 12.The method of claim 11, wherein the portion of the first axial side andthe portion of the second axial side are removed after the new threadsare formed.
 13. The method of claim 11, wherein the portion of the firstaxial side and the portion of the second axial side are removed beforethe new threads are formed.
 14. The method of claim 11, wherein a lengthof the portion of the shoulder that is removed is substantiallyequivalent to an aggregate of a length of the portion of the first axialside and a length of the portion of the second axial side.
 15. Themethod of claim 11, wherein a radial thickness of the body decreasesproceeding from the shoulder toward the first and second axial sides.16. The method of claim 9, wherein the new threads are a continuation ofthe first internal threads, the second internal threads, or both.
 17. Atubular coupling, comprising: a body having a bore formedaxially-therethrough; internal threads formed on an inner surface of thebody, wherein the internal threads were previously used to couple thetubular coupling to a tubular member; new threads formed on the innersurface of the body, wherein the new threads are formed after theinternal threads were previously used to couple the tubular coupling tothe tubular member, and wherein the new threads are a continuation ofthe internal threads; and a shoulder extending radially-inward from thebody with respect to the internal threads and the new threads, whereinthe new threads are positioned axially-between the internal threads andthe shoulder.
 18. The tubular coupling of claim 17, wherein the internalthreads, the new threads, or both comprise at least one kick-out featureincluding at least one rounded or chamfered corner thereof.
 19. Thetubular coupling of claim 17, wherein the body defines: a first groovein an outer surface thereof for receiving a first sealing element; and asecond groove in the outer surface thereof for receiving a secondsealing element, wherein the internal threads and the new threads arepositioned between the first and second grooves.
 20. The tubularcoupling of claim 18, wherein the first sealing element comprises: aradially-outer surface; two or more outer ridges extending outwards fromthe radially-outer surface; a tapered, radially-inner surface; andsubstantially parallel axial sides extending between the radially-outersurface and the tapered, radially-inner surface.